Cascading Stylesheets (CSS) are a mechanism for attaching style information (font, weight, size, color, and so forth) to elements in an HTML document without abusing HTML to do so.
The FreeBSD web site does not currently use CSS. Unfortunately, the look and feel is constructed using abuses of HTML of varying degrees. This should be fixed, and would be a good project for someone looking to contribute to the documentation project.
The FreeBSD DSSSL stylesheets include a reference to a stylesheet, docbook.css, which is expected to appear in the same directory as the HTML files. The project-wide CSS file is copied from doc/share/misc/docbook.css when documents are converted to HTML, and is installed automatically.
This, and other documents, can be downloaded from ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/.
For questions about FreeBSD, read the documentation before contacting <questions@FreeBSD.org>.
For questions about this documentation, e-mail <doc@FreeBSD.org>.